It was the first official conversation between the two men since Leo's papacy began.

"The Holy Father repeated his appeal for international humanitarian law to be fully respected, emphasising in particular the obligation to protect civilians and sacred places, the prohibition of the indiscriminate use of force and of the forced transfer of the population," the Vatican wrote in a statement.

The pope emphasised "the urgent need to provide assistance to those most vulnerable to the consequences of the conflict and to allow the adequate entry of humanitarian aid", it said.

It followed a call on Friday between the pope and Israeli Prime Minister Benjamin Netanyahu, a day after a strike by Israel on Gaza's only Catholic Church that killed three people.

On Sunday, Leo condemned the "barbarity" of the war in Gaza and again called for a peaceful resolution.

The Holy See, which supports a two-state solution, formally recognised the state of Palestine through an agreement signed in 2015, one of the first states in Europe to do so.

In 2014, Israeli and Palestinian presidents Shimon Peres and Abbas planted an olive tree alongside Pope Francis in the Vatican gardens.